1. Field of the Invention
The present invention relates to a branching unit for boring without stopping of fluid suitable for extracting a branch from an existing pipe such as water or gas pipe.
2. Background Art
As described in Japanese Patent Laid Open No. 2002-321109, a construction method in which a part of the existing pipe is drilled with a drill machine having a hole saw has been well-known.
Basic process of this drill construction will be briefly described.
As shown in FIG. 20A, a sealing case 2 consisting of a pair of a first separate casing 21 and a second separate casing 22 covers a part of an existing pipe 1. The first separate casing 21 is provided with a valve body (slice valve) 100. A drill machine 3 is subsequently mounted on the first separate casing 21.
As shown in FIG. 20B, the drill machine 3 operating a hole saw 4, the hole saw 4 rotates its chief axis and drills the existing pipe 1 to make an opening 11. Thereafter, as shown in FIG. 20C, the valve body 100 closes after the hole saw 4 is backed off. After the drill construction, the drill machine 3 is removed from the first separate casting 21, a branch pipe is connected to the first separate casing 21, a valve is opened by moving the valve body 100, thereby a branch construction is finished.